1. Field of the Invention
This invention relates generally to analog to digital conversion and digital to analog conversion and, more particularly, to converting analog signals to digital representations in the presence of digital noise.
2. Description of the Related Art
High performance wireless communication apparatus such as RF receivers, transmitters, and transceivers typically include RF front-end circuitry that operates on an RF signal being received or transmitted. For example, the front-end circuitry may down-convert a received RF signal to baseband and/or up-convert a baseband signal for RF transmission. The RF front-end circuitry typically includes analog circuits such as low noise amplifiers and mixers that have a relatively high sensitivity to noise and interference. The RF circuitry in some applications, such as in mobile communication cellular handsets, may be required to detect signals as small as a few micro-volts or less in amplitude. It is thus often important to minimize noise and interference from sources external or even internal to the communication apparatus.
In addition to the RF front-end circuitry, typical wireless communication apparatus may also include digital processing circuitry that performs various digital functions. The digital processing circuitry may include a variety of specific hardware such as a DSP (digital signal processor), an MCU (microcontroller unit), hardware accelerators, memory, and/or I/O interfaces, among numerous other specific hardware devices.
Unfortunately, the digital processing circuitry of a typical communication apparatus can be a significant source of detrimental noise and interference. More particularly, the digital processing circuitry in a typical high performance communication apparatus produces digital signals with relatively small rise and fall times, or with fast transitions or sharp edges. Furthermore, those signals often have relatively high frequencies. As a result, they generate high frequency interference. These spurious emissions may interfere with, and may adversely impact, the performance of the RF front-end circuitry. Thus, in many systems, the RF front-end circuitry is implemented on an integrated circuit die that is separate from the integrated circuit die on which the digital processing circuitry is implemented.
For various reasons, it may be desirable to integrate the RF front-end circuitry and digital processing circuitry on a single integrated circuit die. However in certain implementations, integration of the RF front-end circuitry and digital processing circuitry on a single integrated circuit may present challenges due to digital noise from the digital processing circuitry.